The present invention relates to a braking apparatus for an electric power tool, which generates braking force in a three-phase brushless motor by causing a short circuit between terminals of the three-phase brushless motor.
For example, in an electric power tool disclosed in Japanese Unexamined Patent Application Publication No. 3-74194, in order to decelerate or stop rotation of a three-phase brushless motor, a so-called short-circuit brake is used, which generates braking force by causing a short circuit between terminals of the motor.
In the short-circuit brake, for example, a set of three switching elements (so-called low-side switches) provided in a current path between each terminal of the motor and a negative electrode of a direct current power source are turned on, and another set of three switching elements (so-called high-side switches) provided in a current path between the each terminal of the motor and a positive electrode of the direct current power source are turned off, thereby causing the motor to generate braking force.
In this manner, in the short-circuit brake, it is possible to brake (decelerate or stop) the motor by merely turning on/off of the switching elements used in the current control of the motor.